Heat-insulating material and process of manufacture



Patent'ed Nov. 18 19 30 I IT ST TES .PATIENT VOFFI CE HAROLD w. GREIDER, or rnrmourn MEETING, .rENNsYLvANfA, Assronon. r THE PHILIP cAnnY MANUFACTURING COMPANY, A CORPORA'lEION or OHIO HEAT-INSULATING MATERIAL AND rnocnss or MANUFACTURE No Drawing. Application filed February This invention relates to heat insulating materials and the process of manufacturing same. 'It is applicable particularly to insulations. comprising 1i ht, bulky, finelydivided ingredients suc alone or mixed with a fibrous binder such as asbestos, or also comprisin other finedivided materials such as diatomaceous earth and calcium carbonate? It is applicable, for example, in the manufacture of 85% magnesla.

" Heretofore, in making heat ihsulation ma-F terial of the'type referred to, finely-divided and/or fibrous ingredients have been made up with water. into a semi-fluid or semi-plastic mix, air or other gas introduced into the mix /prior to molding to make it lighter and more homogeneous, and the mix then forced into filter-molds expelling most of the water by the application ofpressure of about to pounds per square inch while retaining the solids. When the molds are filled,'the pum s are disconnected, the moldsp ened, and the molded formsremoved and t eir dampness V removed by dryin however, undesirably.

duced air or other gas has been substantially expelled by the pressure and drainage of water from the molds and the solid materials have .been' compacted. Moreover shrinkage of the material during drying'also makes the dried product undesirably dense. Accordi gto my invention,-the'above procbe largely improved by forming in the mix priorto molding a foam of minute emulsified bubbles of air or other gas having bubble .films of such/strength that they will success- I fully withstand compacting 'of the materlal during the molding anddrying operations. The forming and stabilizing of a'foam of minute emulsified gasbubbles'of the requisite as magnesia, used Insulation so made is," dense since the intro ess, and product resulting therefrom, may

19,,192 6. Serial No. 89,494.-

also be referred to as gas-emulsifying agents. l hepresence of a gas-emulsifying agent (film-forming'and stabilizing agent) in the water of the mix causes air or other gas introduced or otherwise dispersed therein prior to moldingto emulsifyforming a gaseous emulsion which resists molding under presspre with drainage of water from filter-m'oldsand which is retained in the molded forms. Since a multiplicity of the minute bubbles of gmulsified gas are retained during the to make a heat insulation which :is exceedingly light and which containsiin addition molding-and drying operations, I am able gaseous emulsion. A multiplicity of these minute voids, which may be referred to as dried bubbles of a gaseous emulsion, are of lmicrosco ic size and make'the insulation product ighly micro-porous. The fact that a multiplicityof the voids are of microscopic size permits them to give the-'product increased lightness without sacrifice. of mechanical strength. Moreover. since heat insulation e ciency is increased much more by very minute voids than by coarse volds, the

heat insulation efliciency' of the product is 1 increased to much greater extent than the voids were coarsej Also the resultant prod not is of markedly decreased density and cost per unit volume.- L

forming and-stabilizing agents, and gas- These substances aremost eflective'as filmemulsifying agents, which have pronounced colloidal properties when dispersed in water though some substances which are soluble in water are also satisfactory film-forming and stabilizing agents. While the substances which I ,use according to my invention are not to be regarded as limited by any. theory I Strength and minuteness of size according desgribed as totheir' mode ofaction, those to my. invention is accomplished'by including substances have been found to be partlcularin the water of the mix prior to molding sub-v g I stances which have the property ioftending strong assure-resist ng bubble-films which to form andstabilize bubble-films and which facilitate the formatlpn of bubble films by I therefore call film-forming and stabilizing reducing the'surface tehsion' of water, or by agents. Sincethese substances. produce concentratlon effect of finely-dlvrded parbubblesin the form of anemulsion they may ticles of the substance at the Interface bely satifitctory in 'prodilcing mechanically r or both.

(soaps of fatty acids, either saturated or un-' saturated, having'sixteen or more carbon atoms in the molecule; sulphuric acid com pounds of unsaturated fatt acid glycerides (sulphonated vegetable oils having sixteen or more carbon atomsin the fatty acid radical; sulphonated unsaturated fatty acids, having sixteen or more carbon atoms in the molecule; alkali metal soaps of sulphonated unsaturated fatty acid glycerides (soaps of sulphonated vegetable oils), having sixteen or more carbon atoms in the fatty acid radical; alkali metal soaps of sulphonated unsaturated fatty acids, having sixteen or more carbon atoms in the molecule; saponin; alkali metal resinates (so-called rosin soaps).

These materials may be used alone or a com bination of two or more may be utilized to supplement each other in more eifectively producing the result. These substances above mentioned are of such a nature that they not only create strong bubble-films and emulsify gas but also possess to a greater or less extent the property .of carrying into and holding in or on the films of shells of the bubbles suflicient of the particles of the solid materials to counteract the tendency of the bubbles to rise or float on the top of the mix. Moreover, the particles of finely-divided solids thus held in the bubble-films impart additional strength and stability to the bubbles making them what I call armorplated bubbles and help to prevent the bubbles thus armor-plated fronibeing expelled from a semi-fluid mix containing them as an intermixed foam whenthe mix is forced into molds under pressure with drainage of water from the molds. Substances which are particularly efiective in producing a foam of what I have called armor-plated bubbles be: cause of their strength andstability and tendenpy to not rise to the surface in an aqueous mix, and are therefore preferable for use accordin to my invention, are sulphonated vegeta le and animal oils,soaps of sulphonated oils, and sodium'resinate.

The quantity of the agent which may be used is dependent upon severalfactors, such as the micro-porosity required (the voids-in the product can be increased by using agreater quantity of the agent or decreased by a reduction of same) and the grade of asbestos fiber used (where heavy coarse grades of asbestos are used an increased quantity of agent should preferably be used). Where, also, a mix contains as impurities metallic salts such as solublesalts of calcium, magnesium,

meassa fective condition to obtain the result desired.

Film-forming and stabilizing agents are used according to my invention preferably by incorporating them in the mix prior to molding and then introducing air or other gas as by mechanical agitation, chemical reaction, and the ,like, to form a foam ofminute strength and'stabilityabove" referred to. It' is-preferable according to my invention'to inject or introduce the agent after it has previously been dissolved or colloidally dispersed in hot water while the mix to which it is introduced is in a mixing tank. It may, however, be introduced if desired at any other point in the process provided an mtermixed foam of emulsified gas bubbles stabilized thereby is produced in the mix prior to molding. It is possible also to form a gaseous emulsion created and stabilized by a film-forming and stabilizing agent and then c ommingle the emulsion with the mix prior to molding. The agent" is preferably intro duced into the mixture while the mixture is hot, namely, above normal temperature, as the effectiveness of the agent is increased by warming the mix.

The useof heavy, coarsely-crystalline, nonporous materials, such as cement and plaster of Paris, which set by chemical reaction,'1s not .preferablein connection with the employment of my invention though their use is not necessarily inconsistent with my vention where they are used in a semi-flui mix and the mix is molded under pressure with drainage of water from the molds before substantial setting of the materials by chemical reaction. -Moreover, it is preferable tn employ a mix containing such an excess of water that setting of the mix by chemical reaction would be impossible even though a limited amount of a substance such as cement or plaster of Paris were present. A

mix containing water to the extent of nine times the weight of solids in the mix is preferableinthe employment of my,i1 1vention.

By way of illustration, I will now describe 'my invention as embodied 'in the process, and product resulting therefrom, of manufacturing the magnesia-asbestos insulating ma terial commonly known as magnesia.

According to my invention, theprocess heretofore used in making 85% magnesia may be modified and improved byincluding a semi-fluid .mix comprising magnesia emulsified bubbles. having films of the phonated castor oil, for example, in the proportions of about two pounds to a mix containing 2000 pounds of magnesia by, dry weight (about one-tenth of one per cent.) and then mechanically agitating the mix to form an intermixed emulsion of air introduced by the agitation. Upon molding ,under pressure of about to 50 pounds per uare inch in the usual way in filter-molds wlth drainage of water, the emulsion will resist the pressure of molding and the resultant molded forms of 85% magnesia will contain a multiplicity of thickly interspersed from a semiuid water mix containing magminute voids in excess of those which would occur were my invention not employed;-

While pressures of about 25 to 50 pounds per square inch expel some of the larger bubbles of the foam together with the greater quantity of the water, the pressure is not sufficient to break down and expel the innumerable minute stable emulsified bubbles. The use of lower pressures than those before stated as preferable permits the retcntion of large bubbles, but, although this permits the making of insulation of lighter weight, it results in an insulation which, because of the presence of the large bubbles. is mechanically Weaker in a wet'state, more difiicult to handle, and structurally weaker when dryj After 85% magnesia so made has been molded and subjected to the necessary drying treatment to remove the remaining water, the drying treatment causes the films of the minute bubbles to break down but, although they may change form, they still remain in the structure as dried bubbles of a gaseous emulsion forming innumerable irregular shaped minute cells or voids. Since only a very small quantity of gas-emulsifying agent is required, the cost of employing a gas-emulsifying agent is practically negligible.

If an insulating cement is the product desired instead of molded forms, it may be produced by grinding dried product above described to the desired fineness.

While I have illustrated my invention in detail as applied to the manufacture of85% insulation and have otherwise set forthspecific illustrations in describing my inven tion, I desire to have it understood that s d specific illustrations do not limit the true scope of my invention.

1. Light, highly micro-porous heat insulation material comprising finely-divided solids and a multiplicity of minute voids,

molded under pressure with expulsion of water in filter-molds from a semi-fluid mix containing a foam of minute mechanically strong pressure-resistin bubbles of emulsified gas having films stabilized by a film-forming and stabilizing agent and armoreplated by finelydivided solid ingredients heldin said films by said film-forming andstabilizing agent.

2. Heat insulation material molded under pressure with expulsion of water in filtermolds from a semi-fluid water mix before substantial setting ofthe ingredients of the mix ,by chemical reaction, comprising finely-divided solid ingredients thickly interspersed with minute dried bubbles of a gaseous emulsion, the material surrounding'the multiplicity of voids created in said insulation by said dried bubbles containing minute quantities of a film-forming and stabilizing agent.

3. magnesia molded under a pressure of fromtwenty-five to fifty pounds per square inch with ex ulsion of water in filter-molds pressure with expulsion fof water in filtermolds from a semi-fiuidjvaterl mix before substantial setting of tl1 e ingredients of the mix by chemical reaction, comprisin finely-divided solid ingredients inclu in fiber, thickly interspersed with minute drled'bubbles of a gaseous emulsiom'the material sur-, rounding the multiplicity of voids created in said insulation by saiddried bubbles containing minute quantities of a film-forming and stabilizing agent.

,5. Heat insulation material molded under 1 molds from a semi -fluid water mix before subpressure with expulsion of water in filterstantial setting of the ingredients of the mix by chemical reaction, comprising finely-dis' vided magnesia and asbestos fiber, thickly in,-

terspersed with minute dried bubbles of a gaseous emulsion, the material surrounding the multiplicity of voids created in said insulation by said dried bubbles containing minute quantities of a film-forming and stabilizing agent.

7 Inv a process of makingheat insulation material wherein finely-divided solid ingredients are mixed with water to form a semifluid mix, air or other gas being introduced in water of the mix prior to molding the mix, the mix is molded in filter-molds under pressure with expulsion of water, and the molded forms are thereafter dried, the step comprising including in water of the mix a gasemulsifying agent and emulsifying said gas when introduced in said water of the mix so as to form a stable gaseous emulsion of minute pressure-resisting bubbles in said mix prior to molding said mix, a. multiplicity of said bubbles of emulsified gas being substantially retained during said molding under pressure in filter-molds and a multiplicity of thickly interspersed minute voids being created in the dried product by said retained bubbles of said gaseous emulsion,

8. In a process of. making heat insulation material wherein finely-divided solid ingredients are mixed with water to form asemifluid mix, air or other gas is introduced into the mix prior to molding, the mix is molded in filter-molds under pressure of about 25 to 50 pounds per square inch with expulsion of water and the molded forms are thereafter dried, the stepscomprising including in water of the mix a gas-emulsifying agent and emulsifying said gas when introduced in said mix so as to form a stable gaseous emulsion of l'llll'lllte pressure-resisting bubbles in said mix prior to molding, and thereby retaining a multiplicity of said bubbles of emulsified gas during saidmolding of said mix under pressure in filter-molds so as to form a multiplicity of thickly interspersed minute dried bubbles of a gaseous emulsion in the dried product.

9. In a process of making heat insulation material wherein finely-divided solid ingredients are mixed with water to form a semifluid mix, air or other gas being introduced into water of the mix prior to molding the mix, the mix is molded in filter-molds under pressure of about 25 to 50 pounds per square inch with expulsion of water before substan tial setting of the materials of the mix by chemical reaction and the molded forms are thereafter dried, the steps comprising including in water'of the mix a gas-emulsifying agent, and forming in the mix prior to molding a stable emulsion of said introduced gas containing a multiplicity of minute bubbles having strong pressure-resisting films formed and stabilized by said gas emulsifying agent and thereby retaining a multiplicity of said bubbles of emulsified gas during said molding of said mix under pressure infilter-molds and durin drying soas to form a multiplicity of thic ly interspersed minute dried bubbles of a gaseous emulsion in the dried product. t

10. In a process of making heat insulation material wherein finely-divided inorganic ingredients including magnesia and fiber are mixedlwith water to form a semi-fluid mix, air or other gas being introduced into water of the mix prior to molding the mix, the mix is molded in filter-molds under a pressure of about 25 to 50. pounds per square inch with expulsion of water and the molded forms are thereafter dried, the steps comprising including in waterof said mix comprising magnesia and fiber a gas-emulsifying agent,-

and forming in the mix prior to molding an emulsion containing a multiplicity of microscopic pressure-resisting bubbles of saidmtroduced gas having strong films formed and stabilized by said gas emulsifying agent and armor plated by finely-divided solid ingredients held in said films by said gas-emulsifying agent, a multiplicity of said bubbles of emulsified introduced gas being substantially retained during said molding under pressure in the filter-molds and a multiplicity of thickly interspersed microscopic voids being created in the dried product by said reing including in water of the mix a gasemulsifying agent comprising a sulphonated oil and emulsifying said gas when introduced in said water of the mix-so as to form a stable gaseous emulsion of minute pressure-resisting bubbles in said mix prior to molding said mix, a multiplicity of said bubbles of emuL sified gas being substantially retained during said molding under pressure in filter-molds and a multiplicity of thickly interspersed minute voids being created in the dried prod-' uct by said retained bubbles of said gaseous emulsion. i

12. In a process of making heat insulation material wherein finely-divided solid ingredients are mixed with water to forma semifluid mix, air or other gas being introduced in water of the mix prior to molding the mix, the mixis molded in filter-molds under' pressure with expulsion of-water. and'the molded forms are thereafter dried, the, step com prising including in water of the mix a gas-emulsifying agent comprising an alkali metal soap of sulplionated oil and emulsifying said gas when introduced in said water' of the mix so as to form a stable gaseous emulsion of minute pressure-resisting bub-' bles in said mix prior to molding said mix, -a multiplicity of said bubbles of emulsified gas being substantially retained during said molding under pressure in filter-molds and a'multiplicity of thickly interspersed minute voids being created in the dried product by j it.

ity of said retained bubbles of said gaseous emul- S1011.

13. In a process of making heat insulation material wherein finely-divided solid ingredients are mixed with water to form a semifiuid mix air or other gas being introduced in water of the mix prior to molding the mix, the mix is molded in filter-molds under pressure with expulsion of water, and the molded forms are thereafter dried, the step comprising including in water of the mix a gas-emulsifying agent comprising an alkali metal resinate and emulsifying said gas when introduced in said water of the mix so as to form a stable gaseous emulsion of minute pressure-resisting bubbles in said mix prior to molding said mix, a multiplicity of saidbubbles of emulsified gas being substantially retained during said molding under ressure in filter-molds and a multiplicity ot thiokly interspersed minute voids being created in the dried product by said retained bubbles of said gaseous emulslon. J

14. Heat insulation material molded under pressure with expulsion of water in filtermolds from a semi-fluid water mix before substantial setting of the ingredients of the mix by chemicalreaction, comprising finelydivided solid ingredients thickly interspersed with minute dried bubbles of a gaseous emulsion, the material surrounding the multiplicity of voids created in said nsulation by said dried bubbles containin minute quantities of a film-forming and sta ilizing agent comprising sulphonated oil.

15. Heat insulation material molded under pressure with expulsion of water in filtermolds from a semi-fluid watermix before substantial setting of the ingredients of the mix by chemical reaction, comprising fi'nelydivided solid ingredients thickly interspersed with minute dried bubbles of a gaseous emulsion, the material surrounding the multiplicity of voids created in said insulation by said dried bubbles containing minute quantities of a film-forming and stabilizing agent comprisin alkali metal soap of sulphonated oil.

16. eat insulation material molded under pressure with expulsion of water in v filtermolds from I a semi-fluid Water mix before substantial setting of the ingredients of the mix by chemical reaction, eomprising finelydivided solidingredients thickly interspersed with minute dried bubbles of a gaseous emulsion, the material surrounding the multiplicvoidscreated in said insulation by-said dried bubbles containing minute quantities of a film-forming and stabilizing agent oomprising alkali metal resinate.

In testimony whereof l have signed my name to this s cification.

OLD W. GREDDER. 

